Plug-in switch device



Aug. 14, 1923. 1,464,979

C. C. FARMER Y PLUG-IN SWITCH DEVICE Filed March 25 1921 la 7 W 5 BY%/.

ATTORNEY .To ctt whom t concern.

it linown that i, @man v citizen othe United @ta-te ,l Edgewood, in the county oi. f State oi Pennsylvania.. and acciai limproveme Devices, oi which the n o ,rvitch a .speciswitches, use.

i, i been proiosed to pron i iectric train signet system in the engineer or motiv may signal the cars e conductor y meer. v .n si the above character, it is i isirabie reduce the oit current mach possible and so the signai circuit on each car is normally ieft open and :einst he closed by a piu -in switch bei'ore signaiiing can be carrie on, and fur'- thermore, it is desirable to prevent the use ft the signaliing system except by authora t ns.

ncipai obje oli my invention is e pingin switch for the above rose 1which ca only be operated by a n having a prescribed key adapted for ing the circnit through the plug-in "in the accompanying drawing; Fig. 1 is a plan view of a piugan switch embodying invention; ig. 2 a section of the switch on the line 2-2 of Fig. 1, showing the position of the parts with the key removed;

Vig. 3 a similar section, showing the operating ke in position in the switch; and Fig. 4 an e evational view of the key.

As shown in the drawing, the plug-in switch may comprise a casing 1 havin a chamber 2, containing a block 3 of insu ating material. Fitted in the block 3 are two contact terminals t having connection to the ends of a signal Wire 5 and provided with radial contact lugs 6.

For closing the circuit in the plug-in switch through the wire 5, a key 7 may be provided, as shown in Fig. 4. Said key may have a round shank portlon 8 with radially projecting contact lugs 9 at the outer end.

The open end of the chamber 2 is closed by a cap 10 of insulating material in which is molded an escutcheon plate 11 having an MSE Serrat No. ot.

opening therethrough which corresponds in contour with the contour ofthe contact ing end oi the key 7.

The piate 11 is provided with an inwardiy projecting sleeve portion 12 which acts as a stop for a movable member 13 subjectQ to the pressure of a coil. spring 14.

The key slot through the escutcheon plate 11 is arranged at right angles to the conn tact ings 6, as shown in the drawing.

1n operation, when the key 7 is not in position in the plug-in switch, the circuit through the wire 5 will be o en and the member 13 is prevented from ridging the contact ings 6 by en agement with the sieeve 12, as shown in dig. 2.

1t it is desired to ciose the circuit throngh tbe Wire 5, a key 7 is inserted through the slot in the escntcheon piate 11, raising the member 13 against the resistance of spring 14. The key is then given a quarter turn, so that the contact lugs 9 thereon will aline with the contact ings 6.. When the hand is removed 'trom the key, the spring 14 tbrongh the member 13 Wili press the key ings e into hrm engagement with the logs 6, the sleeve 12 bein slotted at the points 15 so as to permit tage necessary movement of the lugs 9.

1t will now be seen that with the above described construction, the circuit cannot be closed through the wire 5 except by the insertion `of a key having a contour corresponding with the contour of the slot in the escutcheon plate, so that only authorized persons, provided with the proper key, can manipulate the switch.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is

1. The combination with a plug-in switch comprising a casing containing a pair of oppositely disposed contact members and havin a key opening, of a key having op, posite y disposed contact lugs and adapted to be inserted in the key opening and partially rotated to permit the contact lugs to bridge the contact members, a spring, and a movable member subject to the pressure of said spring for pressing the lugs into engagement with the contact members.

2. he combination with a plugin switch comprising a casin containing a pair of oppositely dispose contact members and 

